The invention relates to a positioning apparatus for coils, more particularly of metal strip, to be fitted on to a reeling drum, comprising a lifting carriage for the coil and a measuring device which determines the position of the internal diameter of the coil and whose measured values are evaluated by a control device for the vertical adjustment and movement of the lifting carriage in relation to the reeling drum.
To enable a coil borne by a lifting carriage to be fitted on to a reeling drum, the coil must be removed by the lifting carriage into a vertical position in which the position of the internal diameter of the coil corresponds with that of the reeling drum. To automate this operation it is known to obtain the vertical position of the internal diameter of the coil either directly by means of a sensing element determining the internal diameter at the top and bottom vertex, or indirectly via the external diameter of the coil, by determining the top vertex. The control device for the lifting carriage is then acted upon in dependence on this measuring result. However, experience shows that the operation of the lifting carriage in dependence on said measured values is not enough to ensure the positioning of the coil without colliding with the reeling drum. A cause of such a collision may be that the internal diameter lies eccentrically in relation to the external diameter when the position of the internal diameter is indirectly determined via the external diameter. When the internal diameter is directly determined at diametrically opposite points, collisions may occur because the internal diameter is deformed oval and/or the innermost turn with the start of the coil extends laterally inwards and/or the internal diameter is eccentrically offset laterally. Another fault in the winding of the coil may be that the start (tongue) of the strip is not introduced into the recess provided therefor on the reel. The result is that when the reeling drum expands, the coil is disposed eccentrically on the drum, something which may lead to fluctuations in the pull on the strip when the coil runs off the reeling drum.
It is an object of the invention to provide a positioning apparatus for coils to be fitted on to a reeling drum which ensures that the coils are fitted on to the reeling drum in a trouble-free manner.